The present invention relates to a securing device particularly usable in sports shoes such as ski boots, ice skates or roller skates.
Many kinds of levers used to secure the quarters, the shell or the uppers of sports shoes, such as for example ski boots or ice skates and roller skates, are currently known.
U.S. Pat. No. 3,295,177 discloses a securing lever for a boot having a lever arm that is provided with a set of teeth in a downward region and is arrangeable, at one end, at a shoulder associated with the upper and protruding along a plane which is inclined with respect to said upper.
The lever arm is connected to a ring for securing a flap by means of an adapted metallic plate that keeps the ring facing the set of teeth.
This embodiment, in addition to requiring various steps for the assembly of the components of the lever which increase its production costs, does not have optimum impact-resistance characteristics, especially against impacts occurring along an axis which is transverse to said lever arm.
Such impacts can in fact disengage the lever arm from the shoulder, consequently eliminating the securing action, or break the components.
Swiss patent no. 596,784 discloses a ski boot provided with levers that comprise a lever arm having, in a downward region, a set of teeth with which a metal ring interacts; at its other end, said ring interacts with the boot flap to be secured or with quarter securing bands.
The lever arm has, at one end, a pair of tabs between which a pivot for pivoting the lever arm is located; said pivot is arrangeable at an adapted seat formed on an elastically deformable tab.
Even this embodiment has drawbacks, since any impact affecting the lever arm axially may cause the pivot to leave its seat, thus causing disengagement or breakage.
The possible use of a screw to fix the elastically deformable tab would only partially solve the problem, since it would create a weaker region that might give way if stressed repeatedly.
Furthermore, the use of a screw locks the lever arm in its position.
Similarly, impacts affecting the lever arm transversely to its longitudinal median axis might entail the breakage of the elastically deformable tab, thus eliminating the securing action.
French patent no. 2,410,449 discloses an improved fixing device for ski boots and the like, which comprises a lever arm provided with a set of teeth in a downward region and, on the side opposite to the side gripped by the user, a wedge-like element which interacts with a complementarily shaped seat formed at a tab protruding from the shell.
As an alternative it is possible to use a pivot.
These embodiments have some of the drawbacks described above, since there is still the problem that they are unable to optimally withstand impacts affecting the lever arm, as said arm can disengage from the tab and thus release the shell or the quarters.
It is to be noted that during sports practice these impacts, with the snow or with the poles placed along the racing slope in the case of skiing, or with the ground or the surface of the track in the case of skating, can be very frequent.